1. Field of the Invention
The invention relates generally to analysis of sampled fluids. More particularly, the invention relates to conditioning a sampled hydrocarbon fluid for prior to downstream analysis.
2. Background of the Technology
In the hydrocarbon processing industry, analytical instrumentation is employed at various stages of processing to analyze the chemical composition of the fluids being processed. Typically, the instrumentation analyzes a small sample taken from a hydrocarbon fluid stream undergoing processing. However, prior to introducing the sample to the analytical instrumentation, the sample must be “conditioned” to remove contaminates that may otherwise damage to the instrumentation and/or undesirably skew the analytical results such as product yield results (i.e., desired product volume produced per unit time). In some cases, plant operations may over-react or under-react to the inaccurate results, potentially leading to higher operating cost.
Referring now to FIG. 1, a conventional system 10 for sampling a decoke or green oil fluid stream 15 during hydrocarbon cracking or pyrolysis operations is schematically shown. System 10 includes a fluid conditioner 20 and analytical equipment 30 downstream from conditioner 20. The bulk decoke or green oil (recycle gas) fluid stream 15 is sampled and analyzed to provide insight into the cracking processing. For example, bulk decoke fluid stream 15 may be sampled and analyzed to determine the yield of a desired product (e.g., volume of ethylene or propylene being produced by the cracking process per unit time).
As shown in FIG. 1, a sample 16 is pulled from the bulk decoke fluid stream 15. When sample 16 is initially pulled from the process fluid stream 15, it typically comprises a mixture of a gas 17 to be analyzed and undesirable contaminants 18 such as water and/or relatively heavy hydrocarbons (i.e. C6 and heavier). Contaminants 18 can foul and/or damage downstream fluid transport lines and analytical equipment 30. In addition, contaminants may negatively impact the accuracy of analytical results produced by analytical equipment 30. Consequently, sample 16 is passed through fluid conditioner 20 before being passed to analytical equipment 30. The goal of conditioner 20 is to remove the contaminants 18 from sample 16 prior to analysis. Accordingly, conditioner 20 separates sample 16 into contaminants 18, which are fed back to bulk fluid stream 15, and gas 17, which is passed on to analytical equipment 30 for further analysis. Analytical equipment 30 analyzes gas 17 to determine the yield rate 19 of gas 17, which is communicated to the plant operators. Once analyzed, gas 17 is fed back to bulk fluid stream 15.
Most conventional sample conditioning devices (e.g., conditioner 20) are heat exchangers with manual controls. Such devices allow the relatively hot sample fluid to pass through a cooled pipe that includes a plurality of stacked stainless steel mesh pads. Due to the temperature of the cooled chamber, typically about 60° to 90° F., and the torturous path, defined by the mesh pads, that the sample must navigate through, some of the water and relatively heavy molecular weight components (i.e., components with molecular weights greater than 86) in the sampled fluid will decelerate, form into droplets on the mesh pads, and then fall back down into the hydrocarbon process stream from which they came.
Maintenance of such conventional conditioning devices can be time consuming, labor intensive, and expensive. In particular, most conventional conditioning devices require that the entire device be removed from the pipe string within which it is disposed for service to be performed. In addition, the total surface area provided by the plurality of mesh pads is usually only about 144 in.2, which tends to be more easily fouled. Further, most conventional conditioning devices must be visually inspected and monitored, and manually controlled. In other words, most conventional conditioning devices provide no external insight into the sampling process, the current sample temperature, the status of the conditioner, or the temperature of the cooling air in the conditioner, each of which may allow the plant operators to ascertain whether the analytical data is valid or not.
Accordingly, there remains a need in the art for fluid sampling devices, systems, and methods that offered the potential for improved separation efficiency and insight into the fluid processing being monitored. Such devices and systems would be particularly well received if they could be maintained with reduced effort and expense.